This invention relates to devices for developing a bore in bone tissue and, in particular, to a novel stop element that prohibits insertion of that device into the bone tissue beyond a predetermined depth.
It is common for a dentist to use tools, such as drills, to create bores in bone tissue of a patient""s mouth. Drills come in various styles, sizes and lengths but all have a common goal of creating a bore of a known size. The diameter of the drill dictates the diameter of the bore. However, the length of the bore is determined by the amount of axial movement that the clinician imparts on the drill as he or she inserts it into the bone tissue.
The size of the bore created by the clinician is a critical parameter in the restoration of the dentition of the patient""s mouth. For example, if the length of the bore is too long, it can puncture the sinus cavity if it is placed in the maxillary, or the mandibular canal which contains nerves if it is placed in the mandible. Likewise, the roots of adjacent teeth also can be affected by the size of the bore.
To ensure that the drill bit is inserted into the bone to a known length, the drill bit often contains several markings on it which signify specific depths. For example, a drill bit may have a marking on it that, when located at the surface of the bone, indicates the bore depth is 10 mm. The use of these visual markers is, of course, limited to the clinician""s ability to see the mark as the drill is being inserted into the patient""s mouth. Accordingly, the clinician is required to keep his or her eye on the depth marker as he or she slowly proceeds with the axial movement that causes the drill bit to be inserted deeper and deeper into the bone.
The present invention solves the problem related to the clinician only being able to visualize a depth marking. A detachable stop element is provided that limits the penetration of the drill bit beyond a predetermined axial distance. The drill stop according to the present invention consists of a connecting portion and an extending portion, both having an inner wall defining a bore extending entirely therethrough. The drill bit is inserted through the bore. The connecting portion has a surface that contacts the drill bit for restricting the axial movement of the drill stop relative to the drill bit. The extending portion terminates in a lower end for engaging the bone surrounding the bore to limit the penetration of the drill bit.
With the drill stop surrounding the drill bit, the lower end of the drill stop is positioned adjacent to the drill bit at a predetermined length from the distal end of the drill bit. Accordingly, the clinician is restricted from creating a bore that is longer than the predetermined length since the lower end engages the upper surface of the bone around which the bore is being created.
The drill stop can be made of a frangible material such that it can be served at various positions along that extending portion.